1. Field of the Invention
The present invention relates to a circuit arrangement for switching on or switching off line voltage with respect to a line voltage load, in which an oscillator produces a high frequency pulses which are fed to a transformer by way of a gate circuit, the transformer having a secondary winding which is connected to a control circuit of a triac, and in which the line voltage load and the line voltage are connected in the output circuit of the triac.
2. Description of the Prior Art
A circuit arrangement of the type generally set forth above is known, for example from the publication "Electronics", 1972, Vol. 4, pp. 113-114. In this prior art circuit, the line voltage is connected to a load with the aid of a triac. The triac is triggered by high-frequency pulses which can be connected to a pulse transformer with the aid of a gate circuit. The high-frequency rectangular pulses are produced by a multivibrator. The secondary winding of the transformer is connected in the input circuit or the control circuit of a triac. Therefore, a high-frequency rectangular ac current occurs at the input of the triac. The triac is switched on by means of high-frequency rectangular ac current and, therefore, the load is connected to the line voltage by the triac. This circuit arrangement has the disadvantage that the rectangular pulses must be transmitted by way of the transformer and, thereby rectangular ac current pulses flow in the control circuit of the triac. An essential disadvantage of the circuit arrangement can be seen in that the voltage rise on the load is not limited in the output circuit of the triac at the instant of switch-on.